...there's a good chance that your snakes will breed even without brumation. Brumation does improve fertility rates somewhat, and gives better control over the timing (although not always!)... if you intend to brumate, I definitely recommend housing them separately for the duration of brumation. I also recommend separating them once the female's getting close to laying, at the very latest... and not reintroduced until after the female has put on enough weight to be back up to snuff (double/tripleclutching is possible, and if the female's too weak, it could kill her). If the male proves to be too aggressive with breeding attempts (attempting to breed her repeatedly, especially when she's not in the mood), you should also definitely separate them.
I'm not a big fan of housing snakes together permanently (though I've seen it done), but there are definitely times when it's a bad idea to continue to house them together, even if they seem to be able to cohabitate most of the time. A male's presence will stress the female when she's busy looking for a place to nest... the male may even kick her out of the nestbox, forcing her to lay in the substrate, or perhaps causing her to retain the eggs too long and become eggbound. Sometimes cagemates will remain disinterested in eachother due to familiarity, and won't breed... separating the male for a couple weeks can renew interest.
Basically plan on keeping the male in a separate enclosure for atleast a month and a half (about two weeks before at the very least, and extending to about a month after the female lays), longer depending on the other factors.
-Kat
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"You keep WHAT in your freezer?"
"Mice. And rats. If that bothers you, I can call them 'cows' instead."